INSECTS have nothing analogous to a tongue, though in some there is an organ coiled up spirally within the mouth, which sometimes passes under that name, though it is more generally called the trunk. This must not be confounded with the fleshy tube or proboscis that is found in many insects, especially in bees, wasps, Sze. and which is the organ by which they extract from the flowers their nectarious juice.
A gullet, distinct from the intestinal canal, is found in all the vertebral animals. In the MAMMALIA it dif fers from that of the human subject, in possessing two rows of muscular fibres, which run sacrad in a spiral direction, and cross each other. In the carnivorous quadrupeds, this tube is large and dilatable, but not very muscular ; while in the herbivorous mammalia, especially the ruminantia, its coats are very strong and fleshy.
The gullet of the cetacea is peculiar in its situation with respect to the blowing holes. These animals have no soft palate or -velum pendulum, and their larynx is lengthened out so as to form a pyramidal production, which divides the pharynx in such a manner, that the food may pass on either side of the pyramid. A muscu lar canal extends from the pharynx to the blowing holes, to the margins of which it is attached, and this tube is furnished with circular fibres forming a sphincter mus cle, which, by contracting round the pyramid during deglutition, cuts off the communication between the blowing holes, and the mouth and pharynx.
Tile gullet in BIRDS exhibits some striking differ ences. In the birds of prey it is of a very considerable size, being often larger than the intestinal canal. In all the gallinaceous birds, and in some of the accipitres, this tube is, at the sternal and sacral part of the neck, dila ted into a capacious bag, called the ingluvies, or crop, into which the food is first received, and either under goes a previous maceration, as in the gallinx, or is kept till occasion requires the animal to receive it into the stomach, as in the aceipitres. In some of these birds that live on fishes, the want of the crop is supplied by the great size and dilatability of the gullet. Besides the crop, there is in almost all birds, another dilatation of the gullet, just before its termination in the stomach.
This has been called bulbus glandulosus, and is fur nished with numerous mucous glands, the fluid from which serves to lubricate the passage, and macerate the food.
The gullet of some REPTILES is of a peculiar struc ture. Thus, in the turtle it is extremely large, and its central surface is beset with numerous large pointed processes, of a firm texture, and a white colour, all directed towards the stomach. In the crocodile, the gul let is funnel-shaped. These animals have neither velum pendulum nor epiglottis.
The gullet of SERPENTS is immensely large, or at least extremely dilatable. It is also very long in pro portion to the stomach.
In FISHES, the gullet is very short, and is scarcely to be distinguished from the intestinal canal.
.Organs of Chylification.
An intestinal canal of greater or less extent, and more or less complicated structure, is found in all animals with which we are acquainted, and is indeed the only general and universal organ of digestion. Its differences are exceedingly numerous ; but we must here consider them in a cursory manner.
The most striking differences in the stomachs and intestines of the MAMMALIA, respect the number and situation of the former, and the length of the latter. In the carnivorous quadrupeds, and in some of those that are herbivorous, the stomach is single, and in most of the former its structure differs little from that of the human subject, but its coats are usually stronger and more muscular. In many of these animals the division of the cavity into cardiac and pyloric portions, is very evident, and in a few instances, as in the horse, the ass, the hare, and the rabbit, it is very remarkable and per manent. In these animals, the two portions of the sto mach differ much in structure, one part being smooth and membranous, the other muscular and corrugated in its central surface. Some of the carnivorous quadru peds, however, have the stomach divided into more distinct portions or separate cavities. Thus, in the ham ster there are two stomachs ; in the kangaroo three ; and in the sloths four.